Roller cover



FIG. 1 is a perspective view of a roller cover showing my new design with the broken line showing of a paint roller apparatus being used for illustrative purposes only and forming no part of the claimed design;

FIG. 2 is a side elevation view thereof;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is a bottom plan view thereof. 

The ornamental design for a roller cover, as shown and described. 